Pleiades is the Septuagint translation of:
3598 Kiymah, kee-maw; from the same as 3558; a cluster of stars, i.e. the Pleiades
leiades, seven stars.
Think about Revelation where Yeshua is found in the midst of the seven stars.
So when is the end of Pisces and the beginning of the age of Aquarius? The Age of Aquarius is not part of astronomy. Its an astrological age, which occurs because of a real motion of Earth known as the procession of the equinoxes, which, for example, causes the identity of the pole star to change over time. The cycle of procession lasts 25,800 years, and there are 12 constellations of the Mazzaroth. So, roughly every 2,150 years, the suns position at the time of the March, or vernal, equinox moves in front of a new Mazzaroth constellation. The Age of Aquarius begins when the March equinox point moves out of the constellation Pisces and into the constellation Aquarius.
The International Astronomical Union (IAU) which in the 20th century assumed the duty of officially naming and defining all things astronomical created official constellation boundaries in 1930. From the perspective of astronomy, then, the beginning of the Age of Aquarius is based upon IAU constellation boundaries. According to the Belgian astronomer and mathematical wizard Jean Meeus (bio here), who does adhere to the IAUs definitions, the sun at the March equinox passed from being in front of the constellation Aries and to being in front of the constellation Pisces in 68 B.C. Some astrologers say the Age of Aquarius actually began in 2012. Thats because they believe the star Regulus in the constellation Leo the Lion marked the ancient border between the constellations Leo and Cancer. This star moved to within 30o of the September equinox point in 2012, meaning that Regulus left the sign Leo to enter the sign Virgo in that year. Presuming equal-sized constellations in antiquity, that places the border of the constellations Pisces and Aquarius at 150o west of Regulus, or at the March equinox point.
By this reckoning, the Age of Aquarius started in 2012.